Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology I > Cardiac > Flashcards

Cardiac Flashcards

1
Q

What is the threshold of the SA node

A

-40mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the resting potential of a ventricular fiber

A

-80 to -90

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the resting membrane potential of the SA node

A

-55 to -60mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The SA node is composed of what

A

Special cardiac muscle fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The SA node connects to what

A

Directly to the Atrial fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The AV node receives signal form the SA node ____ after origin

A

.03 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How long is the signal delayed in the AV node

A

.09 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is signal delayed in the AV node

A

due to small size of cells, low amplitude of AP, and slow rate of depolarization during excitation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How long is the final delay of signal in the penetrating bundles of the AV node

A

.04 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How long is the overall delay from the initial origin of the signal until onset of ventricular contraction

A

.16 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The slow conduction in the conductive system of the heart is caused mainly by ______ resulting in an increase in the ________

A

Diminished number of gap junctions along the pathway, resulting in an increase in the resistance to conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the resting membrane potential of the SA node fiber

A

-55 to -60 mV (Threshold= -40mV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why are fast sodium channels in the SA node already inactivated at resting potential

A

Inactivation gates close when membrane potential is less negative than -55mV
- The SA node fiber has a resting membrane potential of -55–60mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is atrial nodal AP slower to develop than ventricular

A

Only slow sodium-calcium channels can open and the fast sodium channels are inactivated due to the resting potential of -55- (-60)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When do the sodium-calcium channels become activated

A

at -40mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how long are the sodium-calcium channels in the SA node open

A

they become inactivated within 100-150msec after opening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When do the potassium channels in the SA node become open

A

at the same time as when the sodium-calcium channels become inactivated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How long do potassium channels remain open in the SA node

A

for a few tenths of a second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the ventricular fiber resting potential

A

-85 to -90

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The atrial nodes do note have what two phases

A

phase 1 & phase 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The AP originating in the SA node generate what

A

The “sinus rhythm”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are action potentials that originate anywhere else than the SA node

A

Ectopic focus or pacemaker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where is the Vagus nerve main distribution in the heart

A

The SA and AV nodes

24
Q

What is the neurotransmitter used by the Vagus nerve

A

Acetylcholine

25
Q

What is a muscarinic receptor

A

A receptor that is located on the SA and AV node that is stimulated by the Vagus nerve

26
Q

What effect does the Vagus nerve have on the SA node

A

it decreases rate of rhythm (negative chronotropic effect)

27
Q

What effect does the Vagus nerve have on the AV junctional fibers

A

slowing transmission of the cardiac impulse into the ventricles

28
Q

What effect does the vagus nerve have to cardiac fiber membrane permeability

A

it increases permeability of the fiber membranes to potassium ions
- hyperpolarization: -65 to -75 rather than -55 to -60 mV

29
Q

Where is the sympathetic innervation of the heart distributed

A

to all parts of the heart, mainly the ventricles

30
Q

What is the neurotransmitter used by the sympathetic nervous system

A

Norepinephrine

31
Q

What effect does norepinephrine have on the heart

A

stimulates beta-1 adrenergic receptors

  • increases depolarization rate (positive chronotropic effect)
  • may increase permeability of fiber membranes to sodium and calcium ions
32
Q

What does the P wave on an EKG represent

A

Atrial depolarization

33
Q

What does the QRS on an EKG represent

A

ventricular depolarization

34
Q

What does the T wave on an EKG represent

A

Ventricular repolarization

35
Q

What do ECG measure

A

The extracellular potential: it is not the same as the potential recorded form an axon when recording the transmembrane potential

36
Q

What is an ECG

A

A graphic representation of the electrical activity in cardiac muscle tissue produced by regions of depolarization and repolarization

37
Q

When does deflection from 0 on an ECG occur

A

only when there is current flow between regions of the heart (when there is variation in the membrane potential in different regions of the heart.) Current flows between regions of different membrane potentials.

38
Q

When does current on an ECG not occur

A

when only the atria and ventricles have different potentials

39
Q

Ventricular muscle has a _______ action potential

A

Monophasic

40
Q

The QRS marks the beginning of what

A

ventricular AP

41
Q

The T wave marks what

A

The end of the ventricular AP

42
Q

No AP is recorded when the ventricle is ______

A

completely polarized or completely depolarized

43
Q

Only when the muscle is partly polarized or partly depolarized does ________

A

Current flow from one part of the ventricle to another

44
Q

Repolarization of the ventricles occurs

A

after the end of the T wave

45
Q

what is the P-Q (P-R) interval

A

beginning of P wave—-> beginning of QRS
- is about 0.16 seconds
note that the 0.16 seconds is the same amount of time that an AP gets from the SA node to the ventricular fibers due to the delay system in the AV node.

46
Q

how long is the Q-T interval

A

0.35 seconds

47
Q

What is the Q-T interval

A

it is the time from ventricular depolarization to ventricular repolarization

48
Q

The P wave represents what phase of the cardiac cycle in the atria

A

Phase 0 (rapid depolarization)

49
Q

The T-wave represents what phase of the cardiac cycle in ventricles

A

phase 3 (repolarization)

50
Q

The QRS represents what phase of the cardiac cycle in ventricles

A

Phase 0 (rapid depolarization)

51
Q

The T wave represents what phase of the cardiac cycle in ventricles

A

Phase 3 (repolarization)

52
Q

In a typical ECG, which of the following waves occurs at the beginning of the contraction of the atria

A

P wave

53
Q

what is typically not seen on an ECG

A

Atrial repolarization

54
Q

Which of the following is the direction of bipolar lead III

A

120 degrees

55
Q

Of the three bipolar leads, which one is connected to both left and right arms

A

Lead I

56
Q

What is the mean electrical axis of the normal ventricles

A

it is 59 degrees

57
Q

what is the amplitude of the SA node

A

about 60mv

resting potential is -55 to -60 and the peak is about

Physiology I (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions